Currently, hermetic/ceramic semiconductor packages are designed around the layout of the device to be built. Traditionally, the bond pads usually lie along both the side and end edges of a semiconductor chip. Bond wires connect the bond pads to bond shelves, or lead fingers, located along the perimeter of the device. Typically, the wire bonds are made of aluminum or gold. The bond pad locations of the device dictate the placement of the bond shelves in the package design and thus dictate the final package dimensions and style availability. For military/avionics and other high reliability uses, the chip is encapsulated in ceramic.
Ceramic packaging is considerably more expensive than typical plastic packaging. Most high reliability applications prefer that ceramic packaging be interchangeable with plastic packaging with respect to size/footprint dimensions and assembly requirements. Accordingly, customers could use plastic parts in trial uses and invest in ceramic parts for their final high reliability use. Designing the package around the original semiconductor chip having bond shelves on all four sides typically results in ceramic packages much larger than their plastic counterparts. While traditional assembly techniques allow the semiconductor chip to be hermetically packaged, they do not allow the flexibility in either the package design or assembly processing necessary to achieve the more compact plastic package footprint and dimensions.
The 16 MB DRAM design is the first generation DRAM configured with center bond pads. Bond wires extending from the bond pad to the bond shelf across much chip real estate poses assembly difficulties as well as reliability risks. The 4 MB DRAM presently has bond shelves formed along all side and end edges of the chip, requiring ceramic packages wider than optimal.
U.S. Pat. No. 5,083,187 issued to Lamson, et al. (hereinafter, the "'187 Patent") describes an integrated circuit device having an electrical circuit connected to a bond pad. A metal layer overlies the bond pad and a metal bump is connected to the metal layer. The metal bump receives power for the electrical circuit. The on metal bump of the '187 Patent eliminates the need for bond wires.
A long felt need exists for a conventionally configured chip that can be conventionally assembled in a narrow ceramic package. Additionally, a long felt need continues to exist for an improved configuration for a chip having center bond pads that provides a compact package that can be hermetically sealed.